Known exploited · Microsoft
CVE-2007-0671: Microsoft Office Excel Remote Code Execution Vulnerability
What it is
Microsoft Office Excel contains a remote code execution vulnerability that can be exploited when a specially crafted Excel file is opened. This malicious file could be delivered as an email attachment or hosted on a malicious website. An attacker could leverage this vulnerability by creating a specially crafted Excel file, which, when opened, allowing an attacker to execute remote code on the affected system.
- Vendor
- Microsoft
- Product
- Office
- Added to KEV
- August 12, 2025
- CISA due date
- September 2, 2025
- Ransomware use
- Unknown
- Weakness
- Not mapped by CISA
What CISA requires
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Forensic triage
No
What to do now
- Find every instance of Office you run, including the forgotten ones, and check its version against the vendor advisory.
- Apply the vendor's fix or mitigation, before September 2, 2025 if you are bound by CISA's deadline, sooner if it faces the internet.
- Assume it was tried against you already: look for signs of exploitation from the date it was added, not from the day you patched.
References
H2 Security
Not sure you are clear?
We check where you run it, patch or mitigate with your team, and look for signs it was already used against you.
Talk to our teamT Academy
Train the engineers who fix it
Security engineering on real hosts in the browser, every objective checked on the machine. The first two lessons of Linux 1 are free.
Start freeSource: CISA Known Exploited Vulnerabilities Catalog (public domain), catalog version 2026.10.01.